WMOD00399

• Title: WMO Training Workshop on Weather Modification for Meteorologists - Lecture Notes
• Date: 12/1/1979
• Weather Modification - Doc Type: Report

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stalled in five clusters each having a gage density of 1 to 3 mi2/gage
(Figure 5). In 1973 the Big Cypress cluster replaced the Talisman clus-
ter, and the mesonet was a15;0 added. In all cases cluster rainfall is
the standard against which the radar-derived rainfall is compared. The
gage-derived water volume and area-averaged rainfall were obtained for
each time it rained in a cl~lster. The former was obtained by integration
of an isohyetal analysis for the length of time it rained in the cluster;
the latter was obtained by dividing the water volume by the cluster area.

Comparisons between gage and radar-derived cluster rainfalls
were made for individual showers and for summed shower rainfalls for the
day. A statistical summary of the gage and radar comparisons for indi-
vidual showers and for summed shower rainfalls within the day are pre-
sented in Tables 4 and 5, respectively. The mean results are stratified
dependin~ on whether the cluster rain volume as determined by the gages
was < 10 m3 or > 105m3. Shower volumes < 103m3 were not considered. The
mean gage and radar correspondence in terms of the factor of difference
(FD) is better if: 1) the rain volume exceeds 105m3, 2) the comparison
is for the day rather than for an individual shower and 3) the comparison
is for 1973 rather than 1972.

Table 4: Gage and Radar Comparisons for Individual Showers

1972 1973 1972 and 1973
Shower
lassi-
fication n FD 11 n FD 11 n FD 11
105m' 79 2.46 2.15 118 2.52 2.24 197 2.49 2.20
> 105m. 22 3.05 3.98 127 1.69 0.73 149 1.89 1.71
Inl
howers 101 2.59 2.65 245 2.09 1.69 346 2.23 2.02

Table "5: Daily Gage and Radar Comparisons

1972 1973 1972 and 1973
Rains
olume
Classi- /I /I /I
fication Days FD 11 lIays FD 11 Days FD a
< 105m' 13 2.72 2.01 11 2.02 1.25 24 2.40 1.71
> 105m' 18 1.46 0.39 66 1.50 0.39 84 1.49 0.39
11 31 1.98 1.45 77 1.51 0.61 108 1.69 0.94